Hops

Hops are the female flower clusters of Humulus lupulus. They are commonly known as seed cones and strobiles. Humulus are used primarily as a flavoring and stability agent in beer, imparting a bitter and tangy flavor. They are also used for various purposes in other beverages and herbal medicine.

Hops are used extensively in brewing today, for their many benefits, including balancing the sweetness of the malt with bitterness, contributing a variety of desirable aromas and flavors, and having an antibiotic effect.

Hops are dried in an oast house before they are used in the brewing process, and there are two main types of hops, bittering hops and aroma hops. Alpha and beta acids are the two main acids in hop resins.

Bittering hops have higher concentration of alpha acids, averaging 5-9%, and are responsible for the bitter flavor in the beer, and have a mild antibiotic/bacteriostatic effect against Gram-positive bacteria. Gram-positive bacteria are the pathogenic bacteria in humans that are stained dark-blue or violet by Gram staining. Bittering hops are boiled for a longer period of time, typically 60–90 minutes, in order to maximize the isomerization of the alpha acids. These hops often have inferior aromatic properties, as the aromatic compounds evaporate during the boil.

Aroma hops have a lower concentration of alpha-acids, about 5%, and are the primary contributors of hop aroma and non-bitter flavor. Aroma hops are often added after the wort has cooled and while the beer ferments, in a technique called 'dry hopping' which gives the hop aroma. Myrcene, Humulene, Caryophyllene, and Faenesene are the four major essential oils in hops, which comprise about 60-80% of the essential oils.

Dual-use hops have high concentrations of alpha acids and good aromatic properties, and can be added to the boil at any time, depending on the desired effect. The flavors and the aromas can be described as grassy, floral, citrus, spicy, piney, lemony and earthy.

Noble hops are traditionally referred to four varieties of hops which are low in bitterness and high in aroma. These four varieties are Hallertau, Tettnanger, Spalt, and Saaz. All are named after the specific region or city where they were first grown or primarily grown.

Besides being an important ingredient in brewery, hops are also an ingredient in Julmust, a carbonated beverage similar to soda, that is popular in Sweden during December, as well as Malta, a type of soft drink in Latin America.

Hops are used as a herbal medicine, as a treatment for anxiety, restlessness, and insomnia. A pillow filled with hops is a popular folk remedy for insomnia. The relaxing effect may be due to the chemical compound dimethylvinyl carbinol. When exposed to light or air, hops will become unstable and lose their potency after a few month's storage.